The invention relates to accounting methods and apparatus for communications networks, such as cellular networks and data networks.
With increased availability of data networks, such as the Internet and intranets, nodes coupled to the data networks can more easily communicate with each other. Popular forms of communications across data networks include electronic mail, file transfer, web browsing, and other exchanges of data. With improved network bandwidth, higher quality voice and/or video communications have also become possible.
Although data networks offer access to a wide array of communications options and information sources, such access is typically not available until the user is sitting at a terminal that is coupled to the data network, such as a terminal located in the home, office, or vehicle. To address this, proposals have been made for providing mobile, cellular computers that can connect to the data networks while moving from place to place. One protocol that has been proposed is the Mobile Internet Protocol (MIP), as described in Request for Comments 2002, entitled “IP Mobility Support,” dated October 1996, and proposed by a working group within the Internet Engineering Task Force (IETF).
As a mobile node moves from location to location, the points of attachments of the mobile node to a data network may change, which may require a new IP address to be associated with the new point of attachment. A point of attachment may be defined as any wireless link between the mobile node and the data network within a given area. A wireless point of attachment may also be provided by a packet-based cellular system, such as a cellular digital packet data (CDPD) system, a general packet radio service (GPRS) system, an enhanced GPRS (EGPRS) system, an EGPRS Compact system, or other packet-based cellular systems.
The Mobile IP protocol allows the mobile node to use either one of two IP addresses, which include a home address that may be assigned “permanently” to a mobile node and remains unchanged regardless of where the node is attached to the data network. The mobile node may also be assigned a care-of address that changes at each new point of attachment. The care-of address includes the visited network's identity number and thus identifies the mobile node's point of attachment. Whenever the mobile node moves, it registers its new care-of address with its home agent located in its home network. To get a packet to a mobile node from its home network, the home agent delivers the packet from the home network to the care-of address. The home agent is a router on a mobile node's home network that delivers packets to roaming mobile nodes and maintains the current location for each mobile node. In a foreign network, which is any network other then the mobile node's home network, a foreign agent, which is a router on a mobile node's visited network, cooperates with the home agent to complete delivery of packets to the mobile node while it is away from the home network. When a mobile node moves away from its home network, it obtains a care-of address on the foreign network by soliciting or listening for special messages (referred to as agent advertisements).
In a traditional cellular network, a mobile user is typically charged for utilizing wireless services provided by a service provider. Typically, a user subscribes to a home service provider, which may have agreements in place with other service providers to allow the wireless user to roam between networks provided by the several service providers. Various types of accounting and billing mechanisms have been implemented to charge users for usage of services as they move between networks provided by different service providers. For example, an accounting architecture is defined by the CDPD standard, described in the CDPD System Specification, Release 1.1, dated January 1995, from the CDPD Forum, Inc. The CDPD protocol provides access to a packet-based network by providing a packet-based overlay to existing voice cellular systems. CDPD detects gaps between voice communications on cellular channels and directs packets of data to those channels. A service provider bills a subscriber for usage based on several parameters, including data packet counts, source and destination addresses, geographical location of the mobile node, and time of transmission. A primary service provider may have to share revenue collected from a subscriber with other service providers whose networks the subscriber may have used during the billing period.
However, conventional systems such as CDPD systems do not bill specifically for usage of packet-based data networks, such as the Internet or intranets, for various services. Such services may include electronic mail, file transfer, electronic commerce, real-time services (such as voice communications over data networks and multimedia conferencing), and other data network services. Further, a general predetermined format for describing accounting information is not available for different service providers to conveniently exchange accounting information. A need thus exists for a method and apparatus that is capable of charging for services utilized on packet-based data networks and that utilizes a uniform format for accounting information.